A vast amount of video data is captured by mobile phone cameras, surveillance cameras and television cameras. A large fraction of this data is highly repetitive, and there is growing demand for identifying the changes in two video clips of the same scene taken at different times. Change detection is an automated process that reduces the amount of data that a human has to inspect to find objects that have appeared, disappeared, or moved, to determine if there are defects in equipment, or to determine if suspicious movements have occurred.